Integrated circuit systems are often operated for a short time or intermittently at a very high power. This is particularly true of power components for applications such as servo drives, soft starters, cranes and lifting or welding appliances. A cooling body is used to transfer the heat generated by high-powered operation out of the integrated circuit system. The cooling body used in high-powered operating conditions is typically dimensioned in such a way that the semiconductors in the integrated circuit system are not overheated even at peak load times. Furthermore, not only must the cooling bodies provide sufficient heat transfer to prevent exceeding the maximum dipole layer temperature, but the cooling bodies must ensured that the temperature does not increase to a temperature that would adversely effect the operating life of the integrated circuit. Accordingly, to prevent shortened operating life, the cooling body must be dimensioned even larger than would be required to transfer the heat during peak operation to maintain the maximum dipole layer temperature. However, in many applications, large cooling bodies lead to problems such as weight, structure size and material use.
For this reason, the short-duration peak dissipated energy is not conventionally carried outwards directly through a cooling body, but is temporarily stored in a heat accumulator. A metal base plate with of sufficient thickness is typically used as a heat accumulator in the case of so-called power modules. However, this has two disadvantages. First, the base plate is very heavy and expensive. Second, the thermal capacity of this type of heat accumulator depends upon the temperature increase.
However, it has been suggested that a latent heat accumulator, as is shown in U.S. Pat. No. 4,057,101, may provide the same thermal capacity as a base plate heat accumulator with a significantly lower weight. The suggested latent heat accumulator is based on the use of a meltable material as a latent heat storage medium. If a meltable material of this kind changes its state of aggregation from solid to liquid, this material absorbs a heat quantity which is referred to as fusion heat. This fusion heat is released if the latent heat storage medium solidifies again. Thus, a material with a high fusion heat may be used as a heat accumulator. If there are temperatures which are higher than the transitional temperature of the meltable material, the heat accumulator will maintain the transitional temperature until such time as the entire latent heat storage material has melted. Thus, a heat accumulator of this kind may provide protection against temporary overheating by the fact that excess heat is temporarily stored until such time as it may be carried away. Possible materials which may be used as latent heat storage media are shown in EP 0 402 304 A1 and in EP 1 087 003 A2, for example.
A further arrangement wherein a latent heat storage medium is used for the cooling of power semiconductor components is shown in U.S. Pat. No. 5,455,458.
The integrated circuit systems with latent heat storage described above, however, suffer from certain problems. The integrated circuit systems with latent heat storage, as described above, can not be economical manufactured. Also, the problem of optimal heat transmission between the semiconductor component generating the heat and the actual latent heat storage medium is not satisfactorily solved.